I wish I could help with the problem, but it does raise an interesting question. Obviously, watchmakers and other metalsmiths can fabricate the little metal pieces that fit inside a watch if parts aren't available.
But the technology to make the chips inside "obsolete" electronic devices like the Manhattan still exists. Is it practical for a one-person shop to make custom chips on a small scale--or even one off.
I get the general impression that this could be a growth industry in the future--the Ferrari F1 team was scouring e-bay to buy old laptops to run the software based engine management on cars from the mid 1990s. A million dollar car (that's the entry fee for Course Cliente, Ferrari's "fantasy racing league") that won't work for the lack of a $50 laptop.
best
allen